The Queen of the Northern Sky

Lately, the James Webb Space Telescope has - for good reason - been getting a lot of attention. In addition, the Perseverance rover just had its first birthday on Mars! But the less well known IXPE (Imaging X-Ray Polarimetry Explorer) just beamed back an amazing new image of Cassiopeia A (Cas A). So, I wanted to look into this a bit more and find out what makes Cas A so interesting.

My first love in science was for anything related to planets and stars and space travel. But it has been a while since I looked into where the constellations got their names. So just for fun, the first brief stop was exploring the history of the name Cassiopeia. And I can assure you the story is like a telenovela.

Sources vary a bit on the details but the constellation was named in the second century for the prideful queen Cassiopeia, from Greek mythology, who made the mistake of boasting that she was more beautiful than the friendly female spirits of the sea called nymphs (kind of like Sirenitas). This angered the great god of the sea Poseidon, who was married to one of the nymphs, so he sent a creature to destroy her kingdom. To satisfy the monster and ease Poseidon’s anger, Cassiopeia's daughter, the princess Andromeda (yes, that Andromeda) was left tied to a rock to be devoured. But just when all hope was lost the hero Perseus, riding his flying horse Pegasus, rode in and rescued her. Naturally he also fell in love with her and married her. The gods, who were watching this all unfold, were so pleased they then proceeded to elevate all these characters to the heavens, where they became stars, and formed the constellation we now know as Cassiopeia.

What is amazing to me about science and astronomy in general is that the knowledge we now have about the planets and the Universe is no less captivating than the stories of old. Our knowledge has gradually replaced mythology but the Universe is still just as wondrous and amazing. The Cassiopeia we know and love is made up of five main stars that form a “W” in the northern sky, circling around Polaris. But it actually contains over a hundred stars that are visible to the naked eye on the darkest night. Some of these are in fact multiple stars that only appear as one. Several stars in the constellation have even been shown to have planets around them. As our ability to find planets improves, maybe one day we’ll find that life may not have been elevated to the heavens in some mythological way. But it does exist out there.

Cassiopeia is actively being studied. Recently the IXPE mission took a look at the supernova Cassiopeia A (Cas A), which is the remnants of a star that exploded around 10,000 years ago. By combining images from the Chandra X-ray Observatory and IXPE the image above was obtained. The magenta color represents new X-ray data from the IXPE while the blue color is higher energy X-rays obtained from Chandra. Also, if you look closely to the center of the picture you will see a small white dot, which could be a collapsed star.

We look to the sky with imagination and awe as many have done before us through the millennia. The stories have changed. The knowledge has changed. But the wonder has remained.

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Cover photo credits: NASA/JPL/Caltech

References:

https://www.constellation-guide.com/constellation-list/cassiopeia-constellation/

https://www.britannica.com/topic/Perseus-Greek-mythology

https://www.thoughtco.com/cassiopeia-constellation-4165137

https://earthsky.org/constellations/

https://chandra.cfa.harvard.edu/photo/2011/casa/

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